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Upgrading to ESXi 5

VMware ESX and VMware ESXi are bare-metal hypervisors that are part of VMware’s Enterprise software hypervisors for servers that run directly on server hardware without requiring an additional underlying operating system. Starting with vSphere 5.0, VMware has discontinued ESX edition and is available only as ESXi. Administrators have to plan and upgrade their existing ESX/ESXi Servers into ESXi 5.0. Also , Administrators can upgrade both ESX 4.x & ESXi 4.x versions of hypervisor to ESXi 5.0.

vSphere Upgrade is a step by step process and has to be carried out in the specified order as indicated below :

  • Upgrade to vCenter 5.0 & vSphere Update manager 5.0
  • Install & Configure vCenter Server Components
  • Upgrade existing ESX/ESXi  4.x to ESXi 5.0
  • Upgrade VMware Tools & VMware Hardware
Prerequisites for upgrading to ESXi 5.0:
  • Please ensure that the vCenter Server and vSphere Update Manager has already been upgraded to vCenter Server 5.0 and vSphere Update Manager 5.0
  • Please ensure that necessary licenses are available for ESXi 5.0. Understand the licensing changes that has been introduced as part of the vSphere 5 before upgrading hosts.
  • In case of VM’s hosted on local disks , Please ensure that backup of VMs hosted on the ESX / ESXi Server that would be upgraded is taken before proceeding with the upgrade.
  • Please note that when ESXi is installed , the boot disk gets repartitioned and any existing data on the boot disk will be lost.  If you have VMs or templates on the boot disk datastore you need to either migrate them onto shared storage (using Storage vMotion), or perform a reliable backup so they can be restored afer the migration.
  • Please note that Service Console Port Group & Local User / Groups on local ESX / ESXi would not be carried during the upgrade.
  • Please note that ESXi is a 64 bit hypervisor and can be installed or upgraded only on Server with 64 bit x86 CPU’s. Also please ensure that Intel VT should be enabled in BIOS
  • Please check VMware Systems Compatibility Guide and ensure that the Server / IO Cards / Storage Components is supported for ESXi 5.0.
  • If you are running ESX / ESXi 3.x in your environment , the hosts have to be upgraded to ESX/ESX4.x first and then upgraded to ESXi 5.0.
  • Please ensure that upgrade is carried out from a supported version of ESX / ESXi ( ESX / ESXi 4.x and above is only supported )
  • Please ensure to perform a host configuration backup before starting the migration
  • Please ensure that the ESX / ESXi Server that would be upgraded has Static IP Address
  • Please ensure that sufficient free space is available on the VMFS datastore for upgrade to happen. VMware recommends a minimum of 50 MB free space. There is also an additional requirement of 350MB free space in the “/boot” partition which would be used as a temporary staging area where Update Manager will copy the ESXi 5.0 image and required upgrade scripts
  • If SAN is connected to a host, Please detach fibre cables before beginning the upgrade
Understand Lopsided Bootbanks:
Please find below extracts from the ESXi Chronicles blog explaining Lopsided bootbanks. You can read the complete post here.
ESXi implements a dual-image architecture wherein the boot disk includes two partitions on which the ESXi image is stored; these partitions are referred to as boot banks.  One boot bank will have the active  image, referred to as the primary boot bank, and the other will have the previous image, referred to as the alternate boot bank.  Anytime you update your image or deploy a new image, the active image is copied from the primary boot bank to the alternate boot bank and the new image is installed into the primary boot bank.
Where lopsided boot banks come into the picture is when upgrading from ESXi 3.5 to ESXi 4.x.  In ESXi 3.5 the size of the boot banks is 48MB.  In ESXi 4.x the size was changed to 250MB.  However, when a host is upgraded from ESXi 3.5 to ESXi 4.x only the size of the primary boot block is grown from 48MB to 250MB.  The size of the alternate boot block is left at 48MB.  This condition of having one boot bank larger than the other is referred to as having “lopsided bootbanks”
The implication of having lopsided boot banks is really pretty minor.  It’s largely transparent and the only limitation is that you won’t be able to use Update Manager to upgrade the host to ESXi 5.0.  Update Manager assumes the boot banks are both at 250MB.  If it detects one boot bank is smaller than the other it will report an invalid boot disk and won’t even try to upgrade.  If this happens you can still upgrade the host using the ESXi 5.0 Installer.   Another option would be to first apply some patches/updates to the host to resize the alternate partition and then upgrade the host using Update Manager.
Understand differences between a fresh installation of ESXi 5.0 & Upgrading to ESXi 5.0
  • Upgraded hosts retain the legacy MSDOS-based partition label and are still limited to a physical disk that is less than 2TB in size
  • Upgraded hosts do not have a dedicated scratch partition. Instead, a scratch directory is created and mounted off a VMFS volume. Aside from the scratch partition, all other disk partitions, such as the boot banks, locker and vmkcore, are identical to that of a freshly installed ESXi 5.0 host
  • The existing VMFS partition is not upgraded from VMFS-3 to VMFS-5. You can manually upgrade the VMFS partition after the upgrade. ESXi 5.0 is compatible with VMFS-3 partitions, so upgrading to VMFS-5 is required only to enable new vSphere 5.0 features
Supported Upgrade Methods 

There are 3 supported upgrade methods to upgrade hosts from ESX/ESXi 4.x to ESXi 5.0. They are as follows:

  • vSphere Update Manager
  • Interactive CD/DVD Upgrade
  • Scripted Upgrade

Point to Consider before Upgrading to VMFS-5

  • VMFS-5 upgraded from VMFS-3 would continue to use the previous file block size which may be larger than the unified 1MB file block size.
  • VMFS-5 upgraded from VMFS-3 continues to use 64KB sub-blocks and not new 8K sub-blocks.
  • VMFS-5 upgraded from VMFS-3 continues to have a file limit of 30720 rather than new file limit of > 100000 for newly created VMFS-5.
  • VMFS-5 upgraded from VMFS-3 continues to use MBR (Master Boot Record) partition type; when the VMFS-5 volume is grown above 2TB, it automatically & seamlessly switches from MBR to GPT (GUID Partition Table) with no impact to the running VMs.
  • VMFS-5 upgraded from VMFS-3 continue to have its partition starting on sector 128; newly created VMFS5 partitions will have their partition starting at sector 2048.

Post Installation Tasks 

  • Ensure that licenses are applied for the upgraded ESXi 5.0 host
  • Ensure that the latest patches are applied for the host
  • Upgrade VMware Tools and VMware Hardware version of the VM’s that are part of the host. Easiest way is to orchestrate the process using vSphere Update Manager
  • Upgrade the datastore from VMFS-3 to VMFS-5
  • Based on requirement , Configure ESXi Dump collector and Syslog for the host.
Reference Links
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